1. Field of the Invention
The present invention relates to the improvement of a thin type linear motion rolling guide unit according to Japanese Patent Application No. 1-116060.
2. Description of the Related Background Art
A linear motion rolling guide unit of the invention disclosed in the above patent application comprises: a long bed member having a U-shaped cross section which is fixedly attached onto a flat plate-shaped attaching member; a long table member which is assembled with the bed member through rolling members; and a rolling member holder which holds a number of rolling members and is arranged between the bed member and the table member, wherein a first rack surface extending in the longitudinal direction is formed on the bottom wall of the holder, a second rack surface is formed on the inner surface of the long table member, when first and second pinions are simultaneously rotated at different peripheral speeds on a common shaft which is come into engagement with each of the rack surfaces and is perpendicularly fixed onto the surface of the attaching member, the engagement conditions between the racks and the pinions are not changed for a change in radial load which is applied to the unit upon operation, the shape of the holder is easily set to a thin shape, the pinion shaft itself is used as a drive shaft of the table, and thereby miniaturizing the whole unit.
However, according to the construction of the unit of the above patent application, since no pressurizing apparatus exists between the second rack of the second rack member and the second pinion, there are problems such that looseness (or play) easily occurs in the engagement portion of the gear and a slight slide phenomenon occurs between the rolling members such as balls and each track surface.
Further, the noises also increase due to the occurrence of the looseness and the unit is abraded early, resulting in an early damage of the unit.